The question that has long tantalized historians, observing the process of Mexico City’s transition from indigenous center to Spanish capital, was what became of the vast indigenous populations organized into “cities and villages…and towns” that so amazed Bernal Díaz, Hernando Cortés, and others. This dissertation aims precisely to answer that question, especially for the late colonial period when it would seem that multiple generations of the indigenous and non-indigenous would have so intermingled in the city as to be the dominant portion of the population. In addition to this demographic hybridization or mestizaje, there is the cultural question: After nearly three hundred years of Spanish presence and domination in New Spain, is it possible to speak of distinctly indigenous cultural customs in Mexico City? To answer these questions, this study focuses on examining the cultural, gendered, and legal customs of eighteenth-century Mexico City residents, concentrating especially on the “Indians” (a designation which must be made by the historian after careful analysis, but which was made by the people at the time as well), using their own criteria to distinguish the indigenous from the mainstream cultural context of the Spanish city. As the most important administrative center in Spain’s American kingdoms, Mexico City’s governing institutions were constantly registering and trying to control the prevalent gendered and cultural customs among its residents, which gives us many rich sources of archival information. As the largest city in Spanish America, Mexico City reveals the multiple levels of living at the center of a vibrant political, ecclesiastic, social, legal, and economic network connected to even the most remote areas of present-day North and Central America. The temporal focus of the research is from 1700 to 1829, a period in which reforms enacted by the Bourbon monarchy and the establishment of a new Mexican nation are thought to have drastically marked structures and practices of bureaucratic and social authority. Through analysis of a variety of Spanish and Nahuatl sources, this study illustrates cultural, gendered, and legal customs practiced by indigenous residents of the city, which marked them as distinctively “Indian” within their mainstream, non-indigenous urban milieu.